Is this a good way of setting up a timer?

[Andrej Mitrovic]

Hey, so is there a reason I'm not allowed to use immutable here:

immutable finalTime = Clock.currTime + dur!"seconds"(5);

Error: cannot implicitly convert expression
(currTime(cast(immutable(TimeZone))opCall()).opBinary(dur(5L))) of
type SysTime to immutable(SysTime)